US9868170B2 - Wire electrical discharge machining apparatus and machining method - Google Patents

Wire electrical discharge machining apparatus and machining method Download PDF

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Publication number
US9868170B2
US9868170B2 US15/127,828 US201415127828A US9868170B2 US 9868170 B2 US9868170 B2 US 9868170B2 US 201415127828 A US201415127828 A US 201415127828A US 9868170 B2 US9868170 B2 US 9868170B2
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machining
workpiece
shape
wire electrode
lower die
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US20170095869A1 (en
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Yuhei Domori
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H7/00—Processes or apparatus applicable to both electrical discharge machining and electrochemical machining
    • B23H7/02—Wire-cutting
    • B23H7/06—Control of the travel curve of the relative movement between electrode and workpiece
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H7/00—Processes or apparatus applicable to both electrical discharge machining and electrochemical machining
    • B23H7/14—Electric circuits specially adapted therefor, e.g. power supply
    • B23H7/20—Electric circuits specially adapted therefor, e.g. power supply for programme-control, e.g. adaptive

Definitions

  • the present invention relates to a wire electrical discharge machining apparatus and a machining method of the wire electrical discharge machining apparatus.
  • Wire electrical discharge machining apparatuses can cut tapers by tilting the wire electrode.
  • Conventional techniques are known that provide correction for the amount of taper angle in accordance with the taper angle (see Patent Literature 1 and Patent Literature 2, for example).
  • Another technique is also known that corrects for errors in a taper angle that occur due to the clearance of the wire guide, by correcting a command movement vector of a machining axis or a taper axis on the basis of the amount of clearance of the wire guide (see Patent Literature 3, for example).
  • Patent Literature 1 Japanese Patent Application Laid-Open No. H04-105820
  • Patent Literature 2 Japanese Patent Application Laid-Open No. H11-165219
  • Patent Literature 3 Japanese Patent Application. Laid-Open No. 2006-035395
  • a force to restore the position of the wire is exerted on the upper die and the lower die in a direction opposite to the direction in which the wire electrode is tilted.
  • This force is denoted as a restoring force.
  • the wire electrode receives a force in a direction away from the machining surface due to electrical discharge. This force is denoted as a repulsive force.
  • the direction of the restoring force and the direction of the repulsive force may be in agreement with each other or mutually opposite at the upper die and at the lower die in accordance with whether the taper-machining shape is a shape that becomes larger toward the top or a shape that becomes larger toward the bottom. As a result, machining accuracy may vary depending on the taper-machining shape.
  • the present invention has been achieved in view of the above, and an object of the present invention is to provide a wire electrical discharge machining apparatus and a machining method that achieve a high machining accuracy to a feasible extent regardless of whether the taper-machining shape is a shape that becomes larger toward the top or a shape that becomes larger toward the bottom.
  • an aspect of the present invention is a wire electrical discharge machining apparatus, including: a wire electrode that generates electrical discharge between the wire electrode and a workpiece to machine the workpiece; an upper die that has a hole to guide the wire electrode and positions the wire electrode above the workpiece; a lower die that has a hole to guide the wire electrode and positions the wire electrode below the workpiece; a drive system that moves any or all of the workpiece, the upper die, and the lower die; and a control device that generates a drive command to operate the drive system on a basis of a machining program that is stored in the control device in advance.
  • the control device determines, during taper machining, whether a type of machining is a type in which the upper die is located on the workpiece side in comparison with the lower die or a type in which the upper die is located on a side opposite to the workpiece in comparison with the lower die on a basis of the machining program and corrects a positional relationship between the upper die and the lower die in accordance with the determined type of machining.
  • a wire electrical discharge machining apparatus changes a correction amount in accordance with the positional relationship between the upper die and the lower die even for an identical inclination angle of a wire electrode, thereby achieving high machining accuracy regardless of whether a taper-machining shape is a shape that becomes larger toward the top or a shape that becomes larger toward the bottom.
  • FIG. 1 is a diagram illustrating the configuration of a wire electrical discharge machining apparatus according to an embodiment of the present invention.
  • FIG. 2 is a diagram for describing an exemplary hardware configuration of an NC control device.
  • FIG. 3 is a diagram illustrating dimensions relating to taper machining.
  • FIG. 4 is a diagram illustrating dimensions relating to the taper machining.
  • FIG. 5 is a diagram for describing a first type.
  • FIG. 6 is a diagram for describing a second type.
  • FIG. 7 is a diagram for describing functional units an NC control device.
  • FIG. 8 is a diagram illustrating an example relationship, which is stored in a displacement amount storage unit, of command angles and the types of taper machining, and vertical-direction displacement amounts.
  • FIG. 9 is a diagram for describing a method of type determination in the case where a first taper machining command is received.
  • FIG. 10 is a diagram for describing the method of the type determination in the case where the first taper machining command is received.
  • FIG. 11 is a diagram for describing the method of the type determination in the case where the first taper machining command is received.
  • FIG. 12 is a diagram for describing the method of the type determination in the case where the first taper machining command is received.
  • FIG. 13 is a diagram for describing a method of the type determination in the case where a second taper machining command is received.
  • FIG. 14 is a diagram for describing the method of the type determination in the case where the second taper machining command is received.
  • FIG. 15 is a diagram illustrating a first machining shape to be subjected to punch machining.
  • FIG. 16 is a diagram illustrating the first machining shape to be subjected to the punch machining.
  • FIG. 17 is a diagram illustrating changes in the vertical-direction displacement amounts during the machining of the first machining shape.
  • FIG. 18 is a diagram illustrating a second machining shape to be subjected to the punch machining.
  • FIG. 19 is a diagram illustrating the second machining shape to be subjected to the punch machining.
  • FIG. 20 is a diagram illustrating changes in the vertical-direction displacement amounts during the machining of the second machining shape.
  • FIG. 1 is a diagram illustrating the configuration of a wire electrical discharge machining apparatus according to an embodiment of the present invention.
  • a wire electrical discharge machining apparatus 100 includes a wire electrode 1 ; a pair of power feed contacts 2 in contact with the wire electrode 1 ; a machining power supply 3 ; and a table 5 on which a workpiece 4 is mounted.
  • the wire electrical discharge machining apparatus 100 also includes an X-axis drive device 6 , which enables a movement on an X axis; a Y-axis drive device 7 , which enables a movement on a Y axis; a U-axis drive device 8 , which enables a movement on a U axis; a V-axis drive device 9 , which enables a movement on a V axis; and an upper die 10 and a lower die 11 , which serve as upper and lower supporting points for the wire electrode 1 when the wire electrode is inclined.
  • an X-axis drive device 6 which enables a movement on an X axis
  • a Y-axis drive device 7 which enables a movement on a Y axis
  • a U-axis drive device 8 which enables a movement on a U axis
  • a V-axis drive device 9 which enables a movement on a V axis
  • the wire electrical discharge machining apparatus 100 also includes an NC control device 12 , which controls the machining power supply 3 , the X-axis drive device 6 , the Y-axis drive device 7 , the U-axis drive device 8 , and the V-axis drive device 9 .
  • the wire electrical discharge machining apparatus 100 also includes a wire bobbin 13 , which supplies the wire electrode 1 ; a feed roller 14 , which changes the traveling direction of the wire electrode 1 and supports the wire electrode 1 ; a lower roller 15 , which changes the traveling direction of the wire electrode 1 ; and a collection roller 16 , which collects the wire electrode 1 after the change in direction by the lower roller 15 .
  • the wire electrode 1 is fed from the wire bobbin 13 and its direction is changed by the feed roller 14 .
  • the wire electrode 1 then passes through a hole of the upper die 10 and a hole of the lower die 11 ; while passing between the upper die 10 and the lower die 11 , the wire electrode 1 performs electrical discharge machining on the workpiece 4 .
  • the upper die 10 which has the hole to guide the wire electrode 1 , positions the wire electrode above the workpiece 4 .
  • the lower die 11 which has the hole to guide the wire electrode 1 , positions the wire electrode below the workpiece 4 .
  • the wire electrode 1 After passing through the lower die 11 , the wire electrode 1 is changed in direction by the lower roller 15 and is collected by the collection roller 16 into a collection box (not shown).
  • the machining power supply 3 applies voltage across each of the power feed contacts 2 and the table 5 .
  • the wire electrical discharge machining apparatus 100 machines the workpiece 4 by generating electrical discharge between the workpiece 4 mounted on the table 5 and the wire electrode 1 in contact with the power feed contacts 2 .
  • the X-axis drive device 6 , the Y-axis drive device 7 , the U-axis drive device 8 , and the V-axis drive device 9 constitute a drive system that moves any or all of the workpiece 4 , the upper die 10 , and the lower die 11 .
  • the X-axis drive device 6 and the Y-axis drive device 7 move the table 5 , as an example.
  • the positions of the upper die 10 and the lower die 11 move in relation to the workpiece 4 on the KY plane.
  • the U-axis drive device 8 and the V-axis drive device 9 move the upper die 10 .
  • the upper die 10 moves in relation to the lower die 11 .
  • the NC control device 12 can achieve taper machining in which the workpiece 4 is machined while the wire electrode 1 is inclined, by controlling the X-axis drive device 6 , the Y-axis drive device 7 , the U-axis drive device 8 , and the V-axis drive device 9 .
  • Inclining the wire electrode 1 means to tilt the traveling direction of the wire electrode 1 in a direction different from a direction perpendicular to the KY plane.
  • the direction perpendicular to the KY plane is referred to, in brief, as a vertical direction hereinafter. Any direction along the KY plane is referred to, in brief, as a horizontal direction.
  • the U-axis drive device 8 and the V-axis drive device 9 may be configured to move the position of the lower die 11 , in place of the upper die 10 .
  • FIG. 2 is a diagram for describing an exemplary hardware configuration of the NC control device 12 .
  • the NC control device 12 includes an arithmetic logic unit 101 ; a main memory 102 ; an auxiliary memory 103 ; an I/O interface 104 ; and a bus 105 .
  • the arithmetic logic unit 101 , the main memory 102 , the auxiliary memory 103 , and the I/O interface 104 are mutually connected via the bus 105 .
  • the arithmetic logic unit 101 is, for example, a CPU (Central Processing Unit).
  • the main memory 102 is a memory that allows faster access than the auxiliary memory 103 .
  • the main memory 102 is made up of, for example, a RAM (Random Access Memory).
  • the auxiliary memory 103 is a memory used as a storage area for different types of data.
  • the auxiliary memory 103 is made up of, for example, a ROM (Read Only Memory), a flash memory, an optical disc, a magnetic disk, or a removable memory device, or a combination of any of them.
  • the I/O interface 104 is an interface device that provides connection to the machining power supply 3 , the X-axis drive device 6 , the Y-axis drive device 7 , the U-axis drive device 8 , and the V-axis drive device 9 .
  • the auxiliary memory 103 has a numerical control program 106 and a machining program 107 , which are stored therein in advance. That is, the auxiliary memory 103 also has a function as a recording medium that has the numerical control program 106 recorded therein.
  • the machining program 107 is a program that describes a procedure to machine the workpiece 4 .
  • the numerical control program 106 is a firmware program that achieves an execution environment for the machining program 107 .
  • the arithmetic logic unit 101 loads the numerical control program 106 from the auxiliary memory 103 to the main memory 102 .
  • the arithmetic logic unit 101 functions as various functional units to be described hereinafter, by executing the numerical control program 106 loaded to the main memory 102 .
  • FIGS. 3 and 4 are diagrams illustrating dimensions relating to the taper machining.
  • FIG. 4 is an enlarged view of the lower die 11 and its vicinity illustrated in FIG. 3 .
  • the upper die 10 is housed in an upper nozzle 10 - 0 .
  • the lower die 11 is housed in a lower nozzle 11 - 0 .
  • a supporting point P 1 is a point located on the XY plane at a position that coincides with the center position of the hole of the upper die 10 and located at a position, in the vertical direction, that coincides with a design supporting point of the upper die 10 .
  • the section of the upper die 10 has a shape of two circles arranged horizontally (a section 10 - 1 and a section 10 - 2 in FIG. 3 ); the position of the supporting point P 1 in the vertical direction coincides with the center position of the section 10 - 1 and the center position of the section 10 - 2 .
  • the upper die 10 and the lower die 11 have annular shapes.
  • a supporting point P 2 is a point located on the XY plane at a position that coincides with the center position of the hole of the lower die 11 and located at a position, in the vertical direction, that coincides with a design supporting point of the lower die 11 .
  • the section of the lower die 11 has a shape of two circles arranged horizontally (a section 11 - 1 and a section 11 - 2 in FIGS. 3 and 4 ); the position of the supporting point P 2 in the vertical direction coincides with the center position of the section 11 - 1 and the center position of the section 11 - 2 .
  • a straight line connecting the supporting point P 1 and the supporting point P 2 has an inclination angle ⁇ 1 from the vertical direction.
  • An inclination angle hereinafter refers to an inclination angle from the vertical direction.
  • the actual supporting points for the wire electrode 1 at the dies 10 and 11 move in the vertical direction from the supporting point P 1 and the supporting point P 2 , respectively.
  • the wire electrode 1 has a diameter that is smaller than the inner diameters of the upper die 10 and the lower die 11 ; this allows the positions of the wire at the dies 10 and 11 to move in the horizontal direction.
  • the actual supporting points for the wire electrode 1 at the dies 10 and 11 move also in the horizontal direction. The movement of the wire position in the horizontal direction will be described hereinafter.
  • a straight line 400 is a straight line along the inclined portion of the wire electrode 1
  • the supporting point P 3 is a point of intersection of a straight line passing through the center position of the hole of the upper die 10 and extending in the vertical direction and the straight line 400
  • the supporting point P 4 is a point of intersection of a straight line passing the center position of the hole of the lower die 11 and extending in the vertical direction and the straight line 400
  • a straight line 500 is a straight line that connects the supporting point P 1 and the supporting point P 2 .
  • L 1 denotes a distance from the supporting point P 1 to the edge of the upper nozzle 10 - 0 in the vertical direction.
  • L 2 denotes a distance from the supporting point P 2 to the top surface of the table 5 in the vertical direction.
  • L 3 denotes a distance from the supporting point P 1 to the supporting point P 3 in the vertical direction.
  • L 4 denotes a distance from the supporting point P 2 to the supporting point P 4 in the vertical direction.
  • L 5 denotes a distance from the edge of the upper nozzle 10 - 0 to the top surface of the table 5 in the vertical direction.
  • L 6 denotes a length of L 1 , L 2 , and L 5 added up.
  • L 3 and L 4 are defined as below. If the relationship of “the height of the supporting point P 3 >the height of the supporting point P 1 ” is satisfied, L 3 has a plus sign. If the relationship of “the height of the supporting point P 2 >the height of the supporting point P 4 ” is satisfied, L 4 has a plus sign.
  • the height refers to an amount indicative of a position in the vertical direction, and a higher position in the drawing plane in FIG. 3 has a larger amount. In the example in FIG. 3 , both of L 3 and L 4 have negative values.
  • a user is allowed to specify the angle ⁇ 1 indirectly by specifying the positions of the dies 10 and 11 from the machining program 107 or to specify the angle ⁇ 1 directly.
  • an angle ⁇ 2 which is the actual inclination angle of the wire electrode 1 , does not agree with the angle ⁇ 1 .
  • the NC control device 12 stores in advance the distance L 3 and the distance L 4 with respect to the angle ⁇ 1 as vertical-direction displacement amounts.
  • the NC control device 12 calculates a correction amount X 1 and a correction amount X 2 , which are deviations in the horizontal direction for correcting the straight line 400 passing between the supporting point P 3 and the supporting point P 4 to the straight line 500 passing through the supporting point P 1 and the supporting point P 2 , on the basis of the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 .
  • the NC control device 12 can perform control such that the actual taper angle agrees with the angle ⁇ 1 , by correcting a distance between the dies 10 and 11 in the horizontal direction by the correction amounts X 1 and X 2 .
  • L 8 denotes a distance between the dies 10 and 11 in the horizontal direction before the correction by the correction amounts X 1 and X 2 .
  • the distance between the dies 10 and 11 in the horizontal direction before the correction by the correction amounts X 1 and X 2 is hereinafter referred to as a pre-correction horizontal distance.
  • L 7 denotes a distance between the dies 10 and 11 in the horizontal direction after the correction by the correction amounts X 1 and X 2 .
  • the distance between the dies 10 and 11 in the horizontal direction after the correction by the correction amounts X 1 and X 2 is referred to as a post-correction distance.
  • the taper machining is classified into two types.
  • FIG. 5 is a diagram for describing a first type of the two types of taper machining.
  • FIG. 6 is a diagram for describing a second type of the two types of taper machining.
  • FIGS. 5 and 6 illustrate examples of punch machining.
  • Punch machining refers to machining in which a portion that is cut off (hereinafter referred to as a core) is the product (the workpiece).
  • the punch machining is in contrast with die machining.
  • Die machining refers to machining in which a portion that remains after a core is cut off is the product.
  • the wire electrode 1 receives a repulsive force in a direction away from the machining surface due to electrical discharge.
  • the machining surface refers to a machining surface of a product.
  • the wire electrode 1 receives a restoring force in a direction in which the tilting of the wire electrode 1 is restored.
  • both of the restoring force and the repulsive force act in directions away from the machining surface of the workpiece 4 at the lower die 11 .
  • the wire position is restrained at a position that is the farthest away from the workpiece 4 in the hole of the lower die 11 .
  • the restoring force acts in a direction toward the machining surface of the workpiece 4
  • the repulsive force acts in a direction away from the machining surface of the workpiece 4 .
  • the wire position moves to a position that is the farthest away from the workpiece 4 in the upper die 10 .
  • a pattern in which the directions of the restoring force and the repulsive force agree with each other at the lower die 11 and the directions of the restoring force and the repulsive force are mutually opposite at the upper die 10 as described above is defined as the first type.
  • the die machining on a shape that becomes larger toward the bottom also falls into the first type. That is, the upper die 10 is located on the side opposite to the product in comparison with the lower die 11 in the first type.
  • both of the restoring force and the repulsive force act in directions away from the machining surface of the workpiece 4 at the upper die 10 .
  • the wire position is restrained at a position that is the farthest away from the workpiece 4 in the hole of the upper die 10 .
  • the restoring force acts in a direction toward the machining surface of the workpiece 4
  • the repulsive force acts in a direction away from the machining surface of the workpiece 4 .
  • the repulsive force is larger than the restoring force
  • the wire position moves to a position that is the farthest away from the workpiece 4 in the lower die 11 .
  • a pattern in which the directions of the restoring force and the repulsive force agree with each other at the upper die 10 and the directions of the restoring force and the repulsive force are mutually opposite at the lower die 11 as described above is defined as the second type.
  • the die machining on a shape that becomes larger toward the top also falls into the second type. That is, the upper die 10 is located on the product side in comparison with the lower die 11 in the second type.
  • the wire position may move in the upper die 10 ; in the case of the second type, the wire position may move in the lower die 11 .
  • the distance L 3 and the distance L 4 may differ depending on whether the type of taper machining is the first type or the second type.
  • the NC control device 12 stores the vertical-direction displacement amounts for each of the two types.
  • FIG. 7 is a diagram for describing the functional units of the NC control device 12 .
  • the NC control device 12 includes a program input unit 121 ; a type determination unit 122 ; a displacement amount storage unit 123 ; a displacement amount calculation unit 124 ; a correction amount calculation unit 125 ; and a correction unit 126 .
  • the program input unit 121 , the type determination unit 122 , the displacement amount calculation unit 124 , the correction amount calculation unit 125 , and the correction unit 126 are functional units that the arithmetic logic unit 101 achieves on the basis of the numerical control program 106 .
  • the displacement amount storage unit 123 is allocated in the main memory 102 or the auxiliary memory 103 .
  • the program input unit 121 reads the machining program 107 .
  • the wire electrode is caused to move on a path obtained by offsetting to the outside of the shape of a product by an amount corresponding to the diameter of the wire electrode 1 .
  • the machining program 107 includes a direction command that specifies the direction in which an offset is made is to the right or to the left with respect to the advancing direction of the wire electrode 1 .
  • the machining program 107 can provide a command for the taper machining by a method in which the angle ⁇ 1 is specified directly or by a method in which the angle ⁇ 1 is specified indirectly by specifying the positions of the dies 10 and 11 .
  • a command in which the angle 91 is specified directly is denoted as a first taper machining command.
  • a command in which the angle ⁇ 1 is specified indirectly by specifying the positions of the dies 10 and 11 is denoted as a second taper machining command.
  • the second taper machining command includes a UV axis command, which provides positioning on the U axis and the V axis, and an XY axis command, which provides positioning on the X axis and the Y axis.
  • the program input unit 121 transmits the machining program 107 that has been read to the type determination unit 122 , the displacement amount calculation unit 124 , and the correction unit 126 .
  • the displacement amount storage unit 123 stores in advance the vertical-direction displacement amounts L 3 and L 4 for each command angle and each type of taper machining.
  • the displacement amount storage unit 123 may store data in any configuration.
  • the displacement amount storage unit 123 stores the vertical-direction displacement amounts L 3 and L 4 in the form of a table having the command angles and the types of taper machining as indexes.
  • FIG. 8 is a diagram illustrating an example relationship, which is stored in the displacement amount storage unit 123 , of the command angles and the types of taper machining, and the vertical-direction displacement amounts L 3 and L 4 .
  • the vertical-direction displacement amounts L 3 and L 4 are stored for each type of taper machining.
  • the vertical-direction displacement amounts L 3 and L 4 are plotted in solid lines in FIG. 8 , although the vertical-direction displacement amounts L 3 and L 4 are actually stored as discrete data in which the vertical-direction displacement amounts L 3 and L 4 are indicated for each command angle at predetermined increment intervals. Dots illustrated in L 3 of the first type indicate such discrete data.
  • the discrete data to be stored in the displacement amount storage unit 123 can be obtained by measuring the positions of the supporting points P 1 and P 2 , the wire position, and the angle ⁇ 2 for, for example, the first type and the second type, with the command angle varied at the increment intervals.
  • the data can be obtained from the taper angle of the workpiece 4 actually machined with the command angle varied at the increment intervals for each of the first type and the second type.
  • the type determination unit 122 determines whether the type of the taper machining is the first type or the second type on the basis of the machining program 107 received from the program input unit 121 .
  • the determination processing by the type determination unit 122 is denoted as type determination.
  • the type determination unit 122 performs the type determination on the basis of the correspondence between the direction indicated by the direction command and the positions of the upper die 10 and the lower die 11 .
  • the direction in which the wire electrode 1 advances is the direction in which the position of machining with respect to the workpiece 4 is moved.
  • FIGS. 9 to 12 are diagrams for describing a method of the type determination in the case where the first taper machining command is received. It is assumed in FIGS. 9 to 12 that the wire electrode 1 advances on a perpendicular line drawn with respect to the drawing plane from the front side of the drawing plane toward the back side of the drawing plane.
  • the sign of a command angle is defined as below. If the upper die 10 is located on the right side of the lower die 11 as viewed in the direction in which the wire electrode 1 advances, the sign of a command angle is plus. If the upper die 10 is located on the left side of the lower die 11 as viewed in the direction in which the wire electrode 1 advances, the sign of a command angle is minus. That is, FIGS. 9 and 11 illustrate cases where the signs of the command angles are plus, whereas FIGS. 10 and 12 illustrate cases where the signs of the command angles are minus.
  • the type of taper machining is determined to be the second type.
  • the type of taper machining is determined to be the first type.
  • the type of taper machining is determined to be the first type.
  • the type of taper machining is determined to be the second type.
  • FIGS. 13 and 14 are diagrams for describing a method of the type determination in the case where the second taper machining command is received.
  • the type determination unit 122 calculates a positional relationship of a program path on the UV axes indicated by a UV axis command and a program path on the XY axes indicated by an XY axis command.
  • a program path on the UV axes refers to a path for the upper die 10 and a program path on the XY axes refers to a path for the lower die 11 .
  • FIG. 13 illustrates a case where the second taper machining command includes an XY axis command that enables a movement on the XY axes from a point A 1 (X 1 , Y 1 ) to a point A 2 (X 2 , Y 2 ) and an UV axis command that enables a movement on the UV axes from a point B 1 (U 1 , V 1 ) to a point B 2 (U 2 , V 2 ).
  • the type determination unit 122 superposes the XY coordinate system and the UV coordinate system such that the X axis coincides with the U axis and the Y axis coincides with the V axis.
  • the type determination unit 122 determines the positional relationship between a vector VA 1 resulting from the XY axis command and a vector VB 1 resulting from the UV axis command. Specifically, the type determination unit 122 partitions a two-dimensional coordinate space, which is accomplished by the superposition of the XY coordinate system and the UV coordinate system, with a straight line obtained by extending the vector VA 1 into a first region 200 , which is a region on the right side with respect to the direction of the vector VA 1 , and a second region 300 , which is a region on the left side with respect to the direction of the vector VA 1 .
  • the type determination unit 122 performs a similar type determination to the case in which the command angle is positive. If the vector VB 1 is present in the second region 300 , the type determination unit 122 performs a similar type determination to the case in which the command angle is negative. If the XY axis command is a command that draws a path of a curved line, it is approximated with a straight line to obtain a vector VA 1 . If the UV axis command is a command that draws a path of a curved line, it is also handled in a similar manner.
  • FIG. 14 illustrates a case where the second taper machining command includes an XY axis command that enables a movement on the XY axes from a point A 3 (X 3 , Y 3 ) to a point A 4 (X 4 , Y 4 ) and a UV axis command that enables a movement on the UV axes from a point B 3 (U 3 , V 3 ) via a point B 4 (U 4 , V 4 ) and a point B 5 (U 5 , V 5 ), in the order set forth, to a point B 6 (U 6 , V 6 ).
  • XY axis command that enables a movement on the XY axes from a point A 3 (X 3 , Y 3 ) to a point A 4 (X 4 , Y 4 )
  • a UV axis command that enables a movement on the UV axes from a point B 3 (U 3 , V 3 ) via a point B 4
  • the type determination unit 122 determines the positional relationship between the vector VA 2 resulting from the XY axis command and the vector VB 2 , the vector VB 3 , and the vector VB 4 resulting from the UV axis command.
  • the vector VB 3 is located on the boundary line between the first region 200 and the second region 300
  • the vector VB 2 and the vector VB 4 are both located in the first region 200 .
  • the type determination unit 122 treats all the vectors resulting from the UV axis command as residing in the region. If, with vectors resulting from a UV axis command including the first vector and the last vector, the last vector is present in a region different from that of the first vector, the type determination unit 122 performs the determination on the basis of the region in which the last vector is present.
  • the type determination unit 122 performs a similar type determination to the case in which the command angle is negative. Note that the type determination unit 122 may perform the determination not on the basis of the region in which the last vector is present. For example, the type determination unit 122 may perform the determination on the basis of the region in which the first vector is present. Alternatively, the type determination unit 122 may perform the determination on the basis of the start point or the end point.
  • the type determination unit 122 performs the type determination on the basis of the direction indicated by the direction command and the positional relationship between the upper die 10 and the lower die 11 .
  • the type determination unit 122 transmits the determination result to the displacement amount calculation unit 124 .
  • the displacement amount calculation unit 124 acquires or calculates the command angle ⁇ from the machining program 107 received from the program input unit 121 . In the case were the taper machining is indicated with the first taper machining command, the displacement amount calculation unit 124 acquires the command angle ⁇ from the first taper machining command. In the case where taper machining is indicated with the second taper machining command, the displacement amount calculation unit 124 calculates the command angle ⁇ on the basis of an XY axis command and a UV axis command included in the second taper machining command.
  • the displacement amount calculation unit 124 searches the displacement amount storage unit 123 using the command angle ⁇ and the type of taper machining received from the type determination unit 122 to acquire the vertical-direction displacement amounts L 3 and L 4 .
  • the displacement amount calculation unit 124 calculates the vertical-direction displacement amounts L 3 and L 4 corresponding to the command angle ⁇ by interpolating groups of discrete data before and after the acquired or calculated command angle.
  • the displacement amount calculation unit 124 transmits the command angle ⁇ and the vertical-direction displacement amounts L 3 and L 4 to the correction amount calculation unit 125 .
  • the correction amount calculation unit 125 calculates the correction amounts X 1 and X 2 using the command angle ⁇ and the vertical-direction displacement amounts L 3 and L 4 received from the displacement amount calculation unit 124 .
  • the correction amount calculation unit 125 then transmits the calculated correction amounts X 1 and X 2 to the correction unit 126 .
  • the correction amount calculation unit 125 performs the calculation by using, for example, expressions below.
  • X 1 L 3 ⁇ tan ⁇ (1)
  • X 2 L 4 ⁇ tan ⁇ (2)
  • the correction unit 126 calculates the pre-correction horizontal distance L 8 on the basis of the machining program 107 received from the program input unit 121 .
  • the correction unit 126 then calculates the post-correction distance L 7 by adding the correction amounts X 1 and X 2 to the calculated pre-correction horizontal distance L 8 .
  • the correction unit 126 calculates drive commands for the X axis, the Y axis, the U axis, and the V axis such that the horizontal distance between the upper die 10 and the lower die 11 agrees with the post-correction distance L 7 .
  • Drive commands for the X axis, the Y axis, the U axis, and the V axis are commands having a temporal granularity finer than those of commands described in, for example, the machining program 107 ; the drive commands are commands per control cycle.
  • a drive command is, for example, a command to specify a movement amount per control cycle.
  • the correction unit 126 generates a drive command by interpolating each command described in the machining program 107 .
  • the correction unit 126 performs the interpolation by a known method.
  • the correction unit 126 also performs smoothing processing before or after the interpolation.
  • the smoothing processing which may be of any type, is, for example, moving average calculation, Gaussian calculation, or weighted moving average calculation.
  • the interpolation of each command described in the machining program 107 can be performed by a functional unit before the correction unit 126 .
  • the program input unit 121 may perform the interpolation and input a second command that is a command generated by the interpolation to the type determination unit 122 , the displacement amount calculation unit 124 , and the correction unit 126 .
  • the correction based on changes in the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 can be performed with a granularity finer than those of commands described in the program input unit 121 .
  • the second command may be a command per control cycle; it does not have to be a command per control cycle.
  • the smoothing processing is performed at any timing after the calculation of the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 .
  • FIGS. 15 and 16 are diagrams illustrating an example machining shape to be subjected to the punch machining.
  • the machining shape illustrated in FIGS. 15 and 16 is denoted as a first machining shape.
  • FIG. 15 is a top view of the first machining shape and
  • FIG. 16 is a perspective view of the first machining shape.
  • directions in which the wire electrode 1 advances and their sequence are indicated with arrows.
  • the wire electrode 1 is caused to advance from the position of P 10 -P′ 10 in the sequence of S 1 , S 2 , S 3 , and S 4 .
  • the machining process of S 1 which is the punch machining on a shape that becomes larger toward the top, falls in the first type of taper machining.
  • the machining process of S 3 which is the punch machining on a shape that becomes larger toward the bottom, falls into the second type of taper machining.
  • the machining processes of S 2 and 34 in which the wire electrode 1 has zero inclination angle, are straight machining.
  • FIG. 17 is a diagram illustrating changes in the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 during the machining of the first machining shape.
  • the vertical-displacement amount L 3 in the machining process of S 1 is different from the vertical-direction displacement amount L 3 in the machining process of S 3 .
  • the smoothing processing causes the vertical-direction displacement amount L 3 to change smoothly in the machining process of S 2 , thereby preventing an abrupt change in the vertical-direction displacement amount L 3 from the machining process of S 1 to the machining process of S 3 .
  • the vertical-direction displacement amount L 4 is also handled in a similar manner.
  • the type determination unit 122 performs the type determination for each second command resulting from the interpolation, it can switch the types in the middle of a machining process indicated by commands described in the program input unit 121 .
  • FIGS. 18 and 19 are diagrams illustrating another example machining shape to be subjected to the punch machining.
  • the machining shape illustrated in FIGS. 18 and 19 is denoted as a second machining shape.
  • FIG. 18 is a top view of the second machining shape and
  • FIG. 19 is a perspective view of the second machining shape.
  • FIG. 20 is a diagram illustrating changes in the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 during the machining of the second machining shape. Dashed and single-dotted lines indicate the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 before the smoothing processing; solid lines indicate the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 after the smoothing processing. As illustrated, if the smoothing processing is not performed, the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 make discontinuous changes at the point of P 22 -P′ 22 and the smoothing processing causes the vertical-direction displacement amount L 3 and the vertical-direction displacement amount L 4 to make smooth changes.
  • the vertical-direction displacement amounts L 3 and L 4 are stored in advance in the displacement amount storage unit 123 for each command angle and each type of taper machining as described above, although the correction amounts X 1 and X 2 may be stored in advance for each command angle and each type of taper machining.
  • the NC control device 12 determines, during the taper machining, whether the type of machining is the second type, in which the upper die 10 is located on the product side in comparison with the lower die 11 , or the first type, in which the upper die 10 is located on the side opposite to the product in comparison with the lower die 11 , on the basis of the machining program 107 .
  • the NC control device 12 then corrects the positional relationship between the upper die 10 and the lower die 11 in accordance with the determination result of the type determination.
  • the wire electrical discharge machining apparatus 100 changes the correction amounts X 1 and X 2 in accordance with the positional relationship between the upper die 10 and the lower die 11 even for an identical inclination angle of the wire electrode 1 in the manner described above, thereby achieving higher machining accuracy regardless of whether the taper-machining shape is a shape that becomes larger toward the top or a shape that becomes larger toward the bottom, in comparison with the case where the correction amounts X 1 and X 2 are not changed in accordance with the type.
  • the NC control device 12 calculates the correction amounts X 1 and X 2 for each type of machining and each inclination angle of the wire electrode 1 .
  • high machining accuracy can be obtained regardless of the inclination angle.
  • the NC control device 12 may further calculate the correction amounts X 1 and X 2 for each inclination direction.
  • the displacement amount storage unit 123 stores the vertical-direction displacement amounts L 3 and L 4 for each type of taper machining, each command angle, and each inclination direction. This can provide high machining accuracy even if the vertical-direction displacement amounts L 3 and L 4 have directional dependency due to the holes of the upper die 10 and the lower die 11 being, for example, rectangular or other reasons.
  • the machining program 107 includes a direction command that specifies the direction in which an offset is made is to the right or to the left with respect to the advancing direction of the wire electrode 1 .
  • the NC control device 12 then performs the type determination on the basis of the direction command. This allows the type of machining to be determined automatically.
  • 00 wire electrical discharge machining apparatus 101 arithmetic logic unit, 102 main memory, 103 auxiliary memory, 104 I/O interface, 105 bus, 106 numerical control program, 107 machining program, 121 program input unit, 122 type determination unit, 123 displacement amount storage unit, 124 displacement amount calculation unit, 125 correction amount calculation unit, 126 correction unit, 200 first region, 300 second region, 400 and 500 straight line.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Mechanical Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
US15/127,828 2014-03-24 2014-03-24 Wire electrical discharge machining apparatus and machining method Expired - Fee Related US9868170B2 (en)

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JP6162745B2 (ja) * 2015-05-13 2017-07-12 ファナック株式会社 加工開始穴を使用したワーク設置誤差補正機能を備えた数値制御装置
CN115151363A (zh) * 2020-02-25 2022-10-04 发那科株式会社 线放电加工机、修正装置以及修正方法
CN113449393B (zh) * 2021-06-25 2024-03-29 西安市群健航空精密制造有限公司 一种阵列孔加工方法
WO2024042625A1 (ja) * 2022-08-24 2024-02-29 ファナック株式会社 支点位置算出方法及び支点位置算出装置
WO2024042626A1 (ja) * 2022-08-24 2024-02-29 ファナック株式会社 支点位置算出方法及び支点位置算出装置

Citations (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61182729A (ja) 1985-02-09 1986-08-15 Fanuc Ltd ワイヤカツト放電加工機のテ−パ加工制御装置
JPH0373223A (ja) 1989-08-15 1991-03-28 Amada Washino Co Ltd ワイヤ放電加工機におけるワイヤ補正方向、テーパの傾き方向の指示および表示方法
US5012063A (en) * 1988-10-05 1991-04-30 Brother Kogyo Kabushiki Kaisha Taper machining device in wire-cut electrical discharge apparatus
JPH03109607A (ja) 1989-09-22 1991-05-09 Mitsubishi Electric Corp Ｃａｄ／ｃａｍ装置
US5086203A (en) * 1988-06-03 1992-02-04 Hitachi Seiko, Ltd. Wire electric discharge machining apparatus
JPH04105820A (ja) 1990-08-28 1992-04-07 Mitsubishi Electric Corp ワイヤ放電加工装置
DE19617894A1 (de) 1995-05-11 1996-11-28 Charmilles Technologies Vorrichtung zum elektroerosiven Bearbeiten
EP0920945A2 (en) 1997-12-03 1999-06-09 Fanuc Ltd Wire discharge machining control device with taper machining correction feature
EP0920944A2 (en) 1997-12-03 1999-06-09 Fanuc Ltd Wire discharge machining control device with offset correction feature
JP2000024839A (ja) 1998-07-06 2000-01-25 Makino Milling Mach Co Ltd ワイヤ放電加工方法および装置
JP2002018647A (ja) * 2000-06-30 2002-01-22 Brother Ind Ltd ワイヤ放電加工機の制御装置及び制御方法，並びに記憶媒体
JP2005199358A (ja) 2004-01-13 2005-07-28 Sodick Co Ltd ワイヤカット放電加工方法、ワイヤカット放電加工制御方法およびワイヤカット放電加工装置
JP2005246557A (ja) * 2004-03-04 2005-09-15 Denso Corp ワイヤガイド装置およびワイヤカット放電加工機
JP2006035395A (ja) 2004-07-29 2006-02-09 Sodick Co Ltd ワイヤカット放電加工方法
US20070068905A1 (en) 2005-09-26 2007-03-29 Fanuc Ltd Wire electric discharge machine
JP2007301666A (ja) * 2006-05-10 2007-11-22 Fanuc Ltd ６軸制御ワイヤ放電加工機
JP2008284613A (ja) 2007-05-15 2008-11-27 Sodick Co Ltd ワイヤカット放電加工装置におけるテーパ方向角度の補正方法
US20100187204A1 (en) 2009-01-29 2010-07-29 Agie Sa Wire electric discharge machining method and apparatus
US20130180866A1 (en) 2011-12-30 2013-07-18 Agie Charmilles Sa Wire cutting method

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103286398B (zh) * 2012-02-29 2016-04-06 昆山徕通机电科技有限公司 线电极以火花放电位置进行垂直校正的装置及其校正方法

Patent Citations (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61182729A (ja) 1985-02-09 1986-08-15 Fanuc Ltd ワイヤカツト放電加工機のテ−パ加工制御装置
US4736086A (en) 1985-02-09 1988-04-05 Fanuc Ltd Taper cutting control unit for wire-cut, electric discharge machine
US5086203A (en) * 1988-06-03 1992-02-04 Hitachi Seiko, Ltd. Wire electric discharge machining apparatus
US5012063A (en) * 1988-10-05 1991-04-30 Brother Kogyo Kabushiki Kaisha Taper machining device in wire-cut electrical discharge apparatus
JPH0373223A (ja) 1989-08-15 1991-03-28 Amada Washino Co Ltd ワイヤ放電加工機におけるワイヤ補正方向、テーパの傾き方向の指示および表示方法
US5047606A (en) 1989-08-15 1991-09-10 Amada Wasino Co., Ltd. Method and device for calculating an offset direction and a tilt direction of the wire electrode of a wire electro-discharge machining apparatus
JPH03109607A (ja) 1989-09-22 1991-05-09 Mitsubishi Electric Corp Ｃａｄ／ｃａｍ装置
JPH04105820A (ja) 1990-08-28 1992-04-07 Mitsubishi Electric Corp ワイヤ放電加工装置
DE19617894A1 (de) 1995-05-11 1996-11-28 Charmilles Technologies Vorrichtung zum elektroerosiven Bearbeiten
US5834726A (en) 1995-05-11 1998-11-10 Charmilles Technologies, S.A. Device for machining by inclined wire cutting electroerosion
JPH11165219A (ja) 1997-12-03 1999-06-22 Fanuc Ltd テーパ加工補正機能付ワイヤ放電加工用制御装置
EP0920944A2 (en) 1997-12-03 1999-06-09 Fanuc Ltd Wire discharge machining control device with offset correction feature
EP0920945A2 (en) 1997-12-03 1999-06-09 Fanuc Ltd Wire discharge machining control device with taper machining correction feature
JPH11165220A (ja) 1997-12-03 1999-06-22 Fanuc Ltd オフセット補正機能付ワイヤ放電加工用制御装置
JP2000024839A (ja) 1998-07-06 2000-01-25 Makino Milling Mach Co Ltd ワイヤ放電加工方法および装置
JP2002018647A (ja) * 2000-06-30 2002-01-22 Brother Ind Ltd ワイヤ放電加工機の制御装置及び制御方法，並びに記憶媒体
JP2005199358A (ja) 2004-01-13 2005-07-28 Sodick Co Ltd ワイヤカット放電加工方法、ワイヤカット放電加工制御方法およびワイヤカット放電加工装置
JP2005246557A (ja) * 2004-03-04 2005-09-15 Denso Corp ワイヤガイド装置およびワイヤカット放電加工機
JP2006035395A (ja) 2004-07-29 2006-02-09 Sodick Co Ltd ワイヤカット放電加工方法
US20070068905A1 (en) 2005-09-26 2007-03-29 Fanuc Ltd Wire electric discharge machine
JP2007083372A (ja) 2005-09-26 2007-04-05 Fanuc Ltd ワイヤ放電加工機
JP2007301666A (ja) * 2006-05-10 2007-11-22 Fanuc Ltd ６軸制御ワイヤ放電加工機
JP2008284613A (ja) 2007-05-15 2008-11-27 Sodick Co Ltd ワイヤカット放電加工装置におけるテーパ方向角度の補正方法
US20100187204A1 (en) 2009-01-29 2010-07-29 Agie Sa Wire electric discharge machining method and apparatus
US20130180866A1 (en) 2011-12-30 2013-07-18 Agie Charmilles Sa Wire cutting method

Non-Patent Citations (6)

* Cited by examiner, † Cited by third party
Title
Communication dated Oct. 18, 2017 from the German Patent and Trademark Office in counterpart application No. 11 2014 006 404.1, 10 pages with translation.
International Search Report for PCT/JP2014/058019 dated Jun. 10, 2014.
Japanese Notification of Reason for Refusal for JP 2014-555032 dated Mar. 17, 2015.
Machine translation of Japan Patent No. 2002-18,647, Jun. 2017. *
Machine translation of Japan Patent No. 2005-246,557, Jun. 2017. *
Machine translation of Japan Patent No. 2007-301,666, Nov. 2017. *

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DE112014006404B4 (de) 2019-10-17
WO2015145529A1 (ja) 2015-10-01
JPWO2015145529A1 (ja) 2017-04-13
CN106163716A (zh) 2016-11-23
JP5797347B1 (ja) 2015-10-21
DE112014006404T5 (de) 2016-12-22
US20170095869A1 (en) 2017-04-06

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